Talk:Variable renewable energy

Table in Comparison Section Dubious

There is no reference provided for the information in the table and the box stating that wind energy is highly not predictable is contradicted in next section. — Preceding unsigned comment added by 71.38.174.85 (talk) 22:49, 22 October 2012 (UTC)

Also, the meaning of the term variability in the table is unclear. For instance, tidal power follows roughly the same pattern each day. In that sense it has little variability. But if you mean the difference between maximum and minimum power produced, it has large variability. --71.38.174.85 (talk) 23:42, 22 October 2012 (UTC)

Wind Power to some extent can be dispatched

It is possible to hold wind power production in reserve in the event of larger than expected demand or failure of another generating facility. Likewise wind energy production can be curtailed if there currently is excess generation. This is actually done at times as it can be done quicker than adjusting the output of a coal fired plant. --71.38.174.85 (talk) 23:42, 22 October 2012 (UTC)

It is possible to hold hydro power in reserve behind dams, could be a easy place to load follow. How about a basic wind farm that generates all it can, all the time. Dougmcdonell (talk) 23:34, 19 January 2016 (UTC)

Of possible interest: "Wind power variability" section of Greenhouse Solutions with Sustainable Energy by Mark Diesendorf; Also some of the work by Mark Z. Jacobson and his colleagues from Stanford. Johnfos (talk) 01:03, 20 January 2016 (UTC)

Wind power can be reduced, but that usually also reduces income and prolongs return of investment, and so is only done when in excess. TGCP (talk) 22:28, 10 April 2016 (UTC)

Pretty much any power source can be turned down; that doesn't make it dispatchable.GliderMaven (talk) 23:15, 10 April 2016 (UTC)

No, base load plants usually can't be turned down gradually - they are either full on or completely off, or have slow ramp rates. Wind parks CAN be seamlessly and quickly adjusted (by SCADA), but is so shortly used (during storm fronts, or due to economy) that it barely qualifies for inclusion here. TGCP (talk) 19:24, 11 April 2016 (UTC)

The term usually used for reducing wind generation when in oversupply is curtailed. Dispatchable generally refers to it being available on demandScorenza (talk) 16:16, 3 November 2020 (UTC)

This article focuses on the short term. The longer term should also be explained; fx hydropower may have larger annual variability than wind power. TGCP (talk) 22:28, 10 April 2016 (UTC)

The use of Future Fiction

I just removed the sentences with the hydrogen powered jet aircraft and shipping. I like the ideas but, they're fiction and not written as such. So please, include your favorite ideas, and identify them as not being done at the present. And when they build the very first one in the whole world, mention that it's an experiment. I've noticed the fiction in several articles, disappointing that the sci-fi is tolerated so well.Dougmcdonell (talk) 23:34, 19 January 2016 (UTC)

Sorry, I had to undo this. If you had read the papers that were referenced you had seen that this is what is written there. Then you came and wrote the complete oposite while leaving the reference in place. That is absolutely a no-go! You cannot make someone claim something who actually wrote the opposite! Please make sure you don't do this any more, because it is a severe violation of citation rules. Furthermore there are hundreds of studies that see hydrogen as a future energy carrier for storage and mobility. One of them was cited here. And it's not science fiction, it's allready reality. There are several prototyps of hydrogen storage in utilization, which have allready proved the technical feasibility of hydrogen or methane storage. Andol (talk) 00:53, 20 January 2016 (UTC)

'variable' as a term

The qualifier 'variable' does not fit very well, as any biogas plant or hydroelectric plant is variable, if it follows a daily cylce as medium load plant. Electric power is produced if prices are high and the plant ramps down if the prices are low. It is not the variability which discriminates wind and solar from hydropower and biomass, it is the dispatchability. The feature results from the storability of the primary energy: you can easily store potential energy by a dam or chemical energy in a heap of energy crops. It is not possible to store wind energy or solar energy before the conversion into electricity, therefore you have to use them when they are available. 'Variable' is any source of electricity which can ramp up and down; it is the question if you can do this according of an input variable (e.g. electricity price, or system load). Therefore, the discriminator is dispatchability or the lack of this feature. In German, we also have the adjective "dargebotsabhängig", but this is difficult to translate: "supply dependent". --Gunnar (talk) 13:55, 13 September 2019 (UTC)

I think you're right from the perspective of explaining the way the different power sources work. Personally I feel the term weather dependent would be helpful, however as this is not commonly used term I don't think wikipedia should be the place to introduce it. Within coomon usage the two terms used are intermittent and variable with proponents of these sources generally favouring the latter and opponents the former (although this is not universally the case). I don't know how wikipedia guidelines suggest this should be resolved when both terms are (slightly) politicised.--Scorenza (talk) 16:15, 3 November 2020 (UTC)

I think variability more refers to the resource than the technology. All power generation is variably as in it's power output can be varied. However, renewables are unique in that variations in power output are uncontrollable. e.g a 200MW gas plant can always produce 200MW but may not most of the time as it is not needed/ too expensive, etc. A 200MW wind farm can not and does not always produce 200MW of energy. Ravenman32 (talk) 01:10, 24 October 2023 (UTC)

Merger discussion

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result of this discussion was merge. Chidgk1 (talk) 14:05, 9 July 2019 (UTC)

---

Intermittent energy source seems to be the same subject so I suggest it is merged in here. Your thoughts? Chidgk1 (talk) 06:20, 30 June 2019 (UTC)

Yes, absolutely. Clayoquot (talk | contribs) 05:55, 1 July 2019 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Needs more reorganising and removal of duplicate info

There is massive redundancy in this article, for instance three sections on solving intermittency. While 'Compensating for variability' is structured best, it seems to be the most outdated/unsourced... Would it be a good idea to simply remove large parts of outdated and unsourced text? Pinging our pruning hero, Chidgk1. Femke Nijsse (talk) 11:45, 10 February 2021 (UTC)

Shall we merge section 3-7 first before updating? I think that makes it easier, and uses our time best? About 70% is going to be binned I think. Femke Nijsse (talk) 17:47, 10 February 2021 (UTC)

I read your comment now - doing that first would probably have been better than the tactical snips I have just made - I have had enough of this article - hope someone else will take over - you should go back to your Wikibreak! Chidgk1 (talk) 19:03, 10 February 2021 (UTC)

Arms are doing much better. Have found a different position to type. Distracted from work, so I'm going to log out till tomorrow :). Femke Nijsse (talk) 19:08, 10 February 2021 (UTC)

Most urgent is to fix outright errors -- with an example I'm now fixing

In "Demand response," the last paragraph was:

Intermittent solar electricity generation has a direct correlation where hot sunny weather drives high cooling demands. This is an ideal relationship between intermittent energy and demand.

No it's not. See Duck curve. So I am deleting that paragraph. Oaklandguy (talk) 02:39, 1 July 2021 (UTC)

Yeah, that was an oversimplification highly dependent on geography. I have seen it mentioned in high-quality sources for certain US regions. FemkeMilene (talk) 06:30, 1 July 2021 (UTC)

Should "capacity credit" be removed or can it be explained better?

The current definition in the article is from a 2008 source and I find it hard to understand.

I was trying to think how that definition could apply to the current GB grid and what % it would result in but I just got confused.

Would it not make more sense to estimate the % of dispatchable power generation needed within GB?

Do people still use "capacity credit" nowadays and if so is there a more understandable definition perhaps with an up to date example? Chidgk1 (talk) 06:10, 6 April 2022 (UTC)

• I am not an expert, yet (1) The concept of CC is still very important. The source quoted is from 2008 for a simple reason: it was in the article for a long time, so I did not change it when updating the definition (using the source). If this is an issue, I can replace it with sources from 2021-2022. (2) The concept is directly applicable to the National Grid in GB, and is one of the reasons why its expenses in the last few years are skyrocketing almost exponentially. I am planning with time to add some text to this extent into Capacity credit. (3) The idea behind the concept is not very complex:

1. Electricity is hard to store, so it needs to be delivered not when the wind turbine is running at full power (or nameplate capacity), and not averaged over a day (as discounted by the capacity factor), but when the customers need it.
2. Electricity is critical for the life of modern humanity, so even short "loss of load events" (there is no article yet, we have more generic blackout) cannot be frequent (or long).
3. Therefore, while planning the large-scale power system, one needs to plan for a "worst case" (a lot of demand, problems with supply). Prior to wind and solar, this was relatively simple: the power was mostly "dispatchable" (i. e., could be switched on and off at will), so the total amount of generation capacity in the system usually matched the worst case consumption (plus a little bit of margin, "reserve", usually few percent of the total power, to allow some power plants to be taken offline for maintenance if a problem occurs).
4. With variable renewable energy (VRE) situation is drastically different: nobody can guarantee that the electricity at the capacity factor level will be there when needed. Therefore an operating reserve (made of dispatchable conventional power stations) is needed to pick up the slack if the sun is behind the clouds and/or the wind is weak. To calculate the requirements for this reserve, one needs to figure out the amount of firm power that the VRE generator can deliver during the times of the peak load. This is usually a much smaller value than the nameplate, the ratio of whatever is guaranteed to the nameplate is the capacity credit. Therefore, the CC of a new wind/solar power plant roughly describes the power of fossil fuel plants that we can retire once the VRE plant is operational.
5. Note that with low capacity credit the system needs a lot of reserve (for example, if you have an offshore wind plant in Texas with a 1 GW nameplate and CC of 7%, you will need also a 0.93 GW conventional power plant on standby).
6. The reserve rarely actually operates and thus does not get any money from selling the electricity. Its owners need to be compensated somehow; this thankless task is frequently performed by National Grids.
7. As VRE penetration increases, the CC of weather-dependent generation goes down. The explanation is simple: let's suppose that we get only 5% of capacity from wind, then the only times when the system will be stressed without the wind is when the load is close to 95% capacity. The chance of such a rare event coinciding with the (also rare) low wind is extremely low (possibly, below the target loss of load probability of 1 event per 10 years), so the system needs little to none reserve power in order to accommodate the wind. However, if 50% of capacity is delivered by wind, the situation changes: now the potentially stressful conditions are at 50% capacity utilization (pretty common), chances of wind dying down during these long intervals become pretty large, and we need much more conventional generation per GW of wind power in reserve to keep the same probability of the blackouts.

--Викидим (talk) 22:55, 6 April 2022 (UTC)

Thanks for that quick and detailed explanation. I have some further questions so I will ask them on the talk page of the article you have created. Chidgk1 (talk) 06:29, 7 April 2022 (UTC)

base load power in Lead?

I did not want to change the lead in any material way without getting input.. perhaps it might pay to mention base load power in the lead (which is mentioned further down) Flibbertigibbets (talk) 15:18, 20 November 2022 (UTC)

Not sure base load is important enough nowadays to mention. Where I live it looks like nuclear will provide the low-carbon baseload in future. Also where I live the problem in future could be seasonal or annual variation rather than variation over days or a few weeks. But this article should take a global view and I am not an expert and don’t know much about other countries. Why do you think baseload is important for this article and what would you write? Chidgk1 (talk) 06:02, 21 November 2022 (UTC)

"Using larger amounts of intermittent power may require upgrades or even a redesign of the grid infrastructure. Options to absorb large shares of variable energy into the grid include using storage, revisiting traditional base load power sources including nuclear, improved interconnection between different variable sources to smooth out supply, using dispatchable energy sources such as hydroelectricity and having overcapacity, so that sufficient energy is produced even when weather is less favourable." Flibbertigibbets (talk) 14:26, 21 November 2022 (UTC)

I am not going to revert that if you put it in but I am not totally convinced - will take a look and see what the body of the article says about baseload and maybe tweak it around a bit if I find anything which seems not too country specific. If anyone else has a view about baseload I would be interested to hear it Chidgk1 (talk) 17:46, 21 November 2022 (UTC)

Body of article does not seem to support what you added above - but I won’t revert as this article is too difficult for me as different countries are so different that I cannot generalize Chidgk1 (talk) 18:17, 21 November 2022 (UTC)

I am not going to change the article without concurrence.. Flibbertigibbets (talk) 20:06, 21 November 2022 (UTC)